Air cleaners of the oil-bath type, generally similar to the present invention, are old and well-known in the art. Such conventional air cleaner is shown and described in the patent to K. F. Russell, U.S. Pat. No. 2,457,321, issued Dec. 28, 1948. Such air cleaners are commonly used for removing dust from an air stream supplying the carburetor of an internal combustion engine. They commonly impinge a dust-laden air stream traveling at relatively high velocity against an oil-bath to pick up oil, deposit some dust in the oil bath, and deflect the air stream outwardly and upwardly into a vertical filter bed which is at least partially coated with such oil to catch dust traveling in the air stream, some of the oil in the filter bed settling downwardly by gravity and returning to the oil bath only when the air flow stops or is slowed down sufficiently.
Although such conventional air cleaners have a high efficiency of removing dust from air passing therethrough, and a relatively high dust-holding capacity, the latter is limited by relatively low recirculation of dust-laden oil from the filter bed back into the oil bath.